US2024416926A1PendingUtilityA1
Method for the dynamic estimation of the pitch of a motor vehicle by means of an image capture sensor
Assignee: Continental Autonomous Mobility Germany GmbHPriority: Nov 9, 2021Filed: Nov 8, 2022Published: Dec 19, 2024
Est. expiryNov 9, 2041(~15.3 yrs left)· nominal 20-yr term from priority
G06V 20/588G06T 2207/30256G06T 2207/10016G06T 2207/30252B60W 40/11G06T 7/70
55
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Claims
Abstract
A method for estimating the pitch of a motor vehicle by an image-acquiring sensor that is located on board the motor vehicle. The method includes at least a first estimating step consisting in estimating a first pitch angle of the sensor using a first estimating method that integrates a drift-avoidance coefficient aiming to limit drift of the estimation of the first pitch angle, a second estimating step that consists in estimating a second pitch angle of the sensor, using a second estimating method, and a fourth step that consists in refining said first pitch angle by increasing the drift-avoidance coefficient to obtain a refined first pitch angle considered as output angle, if at least one first condition is validated.
Claims
exact text as granted — not AI-modified1 . A method for estimating the pitch of a motor vehicle by at least one image-acquiring sensor that is located on board said motor vehicle and that is able to deliver images of the road over which the motor vehicle is moving, the method comprising at least:
a first estimating step consisting in estimating a first pitch angle θ 1 (t) of the sensor using a first estimating method that integrates a drift-avoidance coefficient DAC(t) aiming to limit drift of the estimation of the first pitch angle θ 1 (t), a second estimating step that consists in estimating a second pitch angle θ 2 (t) of the sensor, using a second estimating method, a comparing third step consisting in examining at least a first condition that is validated if the absolute difference between the first pitch angle θ 1 (t) and the second pitch angle θ 2 (t) is greater than or equal to a first predefined threshold, a fourth step that is executed if a criterion is met, the criterion comprising at least validation of the first condition, and that consists in refining said first pitch angle θ 1 (t) by increasing the drift-avoidance coefficient DAC(t) to obtain a refined first pitch angle θ 1aff (t) considered as output angle, and a fifth step that is executed if the first condition is invalidated and that consists in considering said first pitch angle θ 1 (t) such as computed in the course of the first step as output angle.
2 . The method as claimed in claim 1 , wherein the comparing third step consists in examining at least a second condition that is validated if the quality of the estimation of the first pitch angle θ 1 (t) computed in the course of the first step, and if the quality of the estimation of the second pitch angle θ 2 (t) computed in the course of the second step, are each greater than a second predefined threshold, and in that the fourth step is executed if a criterion is met, the criterion further comprising validation of the second condition, and in that the fifth step is executed if the first condition or the second condition are invalidated.
3 . The method as claimed in claim 2 , wherein the comparing third step consists in examining a third condition that is validated if the absolute difference between the first pitch angle θ 1 (t) and a calibration angle θ calib (t) at the current time t is less than the absolute difference between the second pitch angle θ 2 (t) and said calibration angle θ calib (t), or if the calibration angle θ calib (t) is comprised between the first pitch angle θ 1 (t) and the second pitch angle θ 1 (t), the calibration angle θ calib (t) being known at all times and corresponding to the nominal value of the tilt angle of the sensor when the motor vehicle is not moving, and in that the fourth step is executed if a criterion is met, the criterion further comprising validation of the third condition, and in that the fifth step is executed if at least one of said conditions is invalidated.
4 . The method as claimed in claim 1 , further comprising:
a comparing sixth step consisting in examining a fourth condition that is validated if the first pitch angle θ 1 (t) is greater than the second pitch angle θ 2 (t) and the refined first pitch angle θ 1aff (t) is less than the second pitch angle θ 2 (t), or if the first pitch angle θ 1 (t) is less than the second pitch angle θ 2 (t) and the refined first pitch angle θ 1aff (t) is greater than the second pitch angle θ 2 (t), a seventh step that is executed if the fourth condition is validated and that consists in considering said second pitch angle θ 2 (t) such as computed in the course of the second step as output angle, and an eighth step that is executed if the fourth condition is invalidated and that consists in considering said refined first pitch angle θ 1aff (t) as output angle.
5 . The method as claimed in claim 1 , wherein the first method for estimating the first pitch angle θ 1 (t) of the sensor comprises at least:
a first phase of computing a pitch angle of the sensor estimated by integrating the relative movement of the sensor ( 12 ) θ int (t) at a current time t, using the following equation:
θ
int
(
t
)
=
θ
1
(
t
-
1
)
-
θ
rel
(
t
)
with:
i. θ 1 (t−1) the first pitch angle θ 1 (t) of the sensor at a previous time t−1, and
ii. θ rel (t) a relative angle of the sensor at the current time t that expresses the angle of the sensor between said previous time t−1 and the current time t, and
a second phase of estimating the first pitch angle θ 1 (t) of the sensor, using the following equation:
θ
1
(
t
)
=
θ
int
(
t
)
+
DAC
(
t
)
*
(
θ
calib
(
t
)
-
θ
int
(
t
)
)
with:
i. θ 1 (t) the first pitch angle of the sensor, at the current time t,
ii. θ int (t) the pitch angle of the sensor estimated by integrating the relative movement of the sensor in the course of the preceding computing first phase, at the current time t,
iii. DAC(t) the drift-avoidance coefficient, comprised between zero and one, at the current time t, and
iv. θ calib (t) a calibration angle at the current time t, which is known at all times and which corresponds to the nominal value of the tilt angle of the sensor when the motor vehicle is not moving.
6 . The method as claimed in claim 1 , wherein the drift-avoidance coefficient DAC(t) depends partly on the acceleration of the motor vehicle and partly on the relative movement of the sensor between the current time t and a previous time, the estimating second phase comprising computing the drift-avoidance coefficient DAC(t) using the following equation:
DAC
(
t
)
=
min
(
min
(
DAC
rel
(
t
)
,
DAC
a
→
(
t
)
)
)
with:
DAC rel (t) a relative drift-avoidance coefficient that depends on the movement of the sensor and that is obtained using the following equation:
DAC
r
e
l
(
t
)
=
DAC
MaxRel
*
(
1
-
min
(
∫
t
-
NRel
t
❘
"\[LeftBracketingBar]"
θ
rel
(
x
)
❘
"\[RightBracketingBar]"
θ
AMR
dx
,
1
)
)
with DAC MaxRel a predetermined maximum value of the relative drift-avoidance coefficient DAC rel (t), Nrel a predetermined number corresponding to the selected value of the number of previous times used to determine the relative drift-avoidance coefficient DAC rel (t), θ rel (t) the relative angle of the sensor at the current time t, and θAMR a predetermined empirical maximum value of the relative angle of the sensor at the current time t θ rel (t), and
DAC {right arrow over (a)} (t) an acceleration drift-avoidance coefficient that depends on the acceleration of the motor vehicle, and that is obtained using the following equation:
DAC
a
→
(
t
)
=
DAC
max
a
→
*
(
1
-
min
(
∫
t
-
Na
t
❘
"\[LeftBracketingBar]"
a
→
(
x
)
❘
"\[RightBracketingBar]"
a
→
AMR
dx
,
1
)
)
with DAC max{right arrow over (a)} a predetermined maximum value of the acceleration drift-avoidance coefficient DAC {right arrow over (a)} (t), Na the predetermined number corresponding to the selected value of the number of previous times used to determine the acceleration drift-avoidance coefficient DAC {right arrow over (a)} (t), {right arrow over (a)}(t) the acceleration of the motor vehicle at the time t, and {right arrow over (a)}AMR a predetermined empirical maximum value of the acceleration {right arrow over (a)}(t) of the motor vehicle,
and in that, in the course of the fourth step, the drift-avoidance coefficient DAC(t) is increased by increasing the predetermined maximum value DAC MaxRel of the relative drift-avoidance coefficient DAC rel (t) and by increasing the predetermined maximum value DAC max a of the acceleration drift-avoidance coefficient DAC {right arrow over (a)} (t).
7 . The method as claimed in claim 1 , wherein a penalty drift-avoidance coefficient DAC pen (t) is added to the drift-avoidance coefficient DAC(t) when the measured longitudinal acceleration of the motor vehicle is inconsistent with the variation in the first pitch angle θ 1 (t) of the sensor.
8 . The method as claimed in claim 7 , wherein the penalty drift-avoidance coefficient DAC pen (t) is obtained using the following equation:
DAC pen (t)=max(DAC MaxPen ({right arrow over (a)}(t)*θ int (t)), 0) with DAC MaxPen a predetermined maximum value of the penalty drift-avoidance coefficient DAC pen (t), {right arrow over (a)}(t) the longitudinal acceleration of the motor vehicle and θ int (t) the pitch angle of the sensor estimated by integrating the relative movement of the sensor at a current time t.
9 . The method as claimed in claim 6 , wherein the drift-avoidance coefficient DAC(t) is obtained using the following equation:
DAC(t)=min(min(DAC rel (t),DAC {right arrow over (a)} (t))+DAC pen (t),1) with DAC rel (t) the relative drift-avoidance coefficient that depends on the movement of the sensor, DAC {right arrow over (a)} (t) the acceleration drift-avoidance coefficient and DAC pen (t) the penalty drift-avoidance coefficient.
10 . The method as claimed in claim 5 , wherein the quality of the estimation of the first pitch angle θ 1 (t) depends on the quality of the relative angle θ rel (t) and on the quality of the calibration angle θ calib (t).
11 . The method as claimed in claim 1 , wherein the second method for estimating the second pitch angle θ 2 (t) of the sensor consists in processing the images acquired by the sensor with a view to recognizing therein, in each image, the shape of line markings of the road on which the motor vehicle is being driven and to deducing therefrom the estimation of the second pitch angle θ 2 (t).
12 . The method as claimed in claim 11 , wherein the second method for estimating the second pitch angle θ 2 (t) of the sensor consists in:
analyzing at least one image acquired by the sensor at a time t with a view to recognizing line markings of the road in said image, and selecting a plurality of points belonging to the line markings,
defining a vanishing point where said line markings cross, and
comparing the position of said vanishing point with the position of the optical center of the sensor with a view to estimating the second pitch angle θ 2 (t) of the sensor.
13 . The method as claimed in claim 2 , wherein the quality of the estimation of the second pitch angle θ 2 (t) depends on the number of selected points belonging to the line markings and on the length of said line markings visible in the acquired image.
14 . The method as claimed in claim 1 , wherein the first pitch angle θ 1 (t) of the sensor is a pitch angle that corresponds to an angular movement of the sensor about a transverse axis that on the whole is perpendicular to the longitudinal path of the motor vehicle.
15 . A device for dynamically estimating the pitch of a motor vehicle by at least one image-acquiring sensor that is located on board said motor vehicle, said device being intended to implement the method according to claim 1 , said device comprising at least one image-acquiring sensor that is mounted on said vehicle and a processing unit for determining the first pitch angle θ 1 (t) and the second pitch angle θ 2 (t) of the sensor.
16 . The method as claimed in claim 12 , wherein the quality of the estimation of the second pitch angle θ 2 (t) depends on the number of selected points belonging to the line markings and on the length of said line markings visible in the acquired image.
17 . The method as claimed in claim 7 , wherein the drift-avoidance coefficient DAC(t) is obtained using the following equation:
DAC(t)=min(min(DAC rel (t),DAC {right arrow over (a)} (t))+DAC pen (t),1) with DAC rel (t) the relative drift-avoidance coefficient that depends on the movement of the sensor ( 12 ), DAC {right arrow over (a)} (t) the acceleration drift-avoidance coefficient and DAC pen (t) the penalty drift-avoidance coefficient.
18 . The method as claimed in claim 8 , wherein the drift-avoidance coefficient DAC(t) is obtained using the following equation:
DAC(t)=min(min(DAC rel (t),DAC {right arrow over (a)} (t))+DAC pen (t),1) with DAC rel (t) the relative drift-avoidance coefficient that depends on the movement of the sensor, DAC {right arrow over (a)} (t) the acceleration drift-avoidance coefficient and DAC pen (t) the penalty drift-avoidance coefficient.Join the waitlist — get patent alerts
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